alarm keeps going off even when not set to on

Hello, even though you have been "running the car and battery is fine" - it's probably not that the battery is fine. You've had the battery tested professionally? Low voltage can indeed cause malfunctioning alarm operation. What kind of alarm is this? Subaru factory installed alarm? Aftermarket installed alarm? Keep in mind that for factory installed alarms, a door ajar switch that is malfunctioning can cause false alarm activations also. There are multiple possible causes, and hands on testing is needed. www.repairpal.com/repair-shops